Given a binary tree, find its maximum depth.
The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
1 class Solution {
2 public:
3 int maxDepth(TreeNode *root) {
4 if(!root) {
5 return 0;
6 }
7 int depth = 1 + max(maxDepth(root->left), maxDepth(root->right));
8 return depth;
9 }
10 };
Maximum Depth of Binary Tree,布布扣,bubuko.com
原文：http://www.cnblogs.com/zhengjiankang/p/3646328.html